1. Field of the Invention
The present invention relates to a rotor of a synchronous induction motor which starts using induction torque and carries out synchronous operation using reluctance torque and a compressor employing the synchronous induction motor.
2. Description of Related Art
In a conventional synchronous induction motor, plural slits and slots are provided on a rotor iron core formed by electromagnetic steel sheets, and in order to let the magnetic flux easily flow in a direction of a d axis, a gas vent hole is formed into an oval shape that is stretched in the direction of d axis, so that efficiency of the synchronous induction motor is tried to be improved (refer to Patent Document 1, for example).
Patent Document 1: JP2003-153511 (page 5, FIG. 6)
In a rotor of a conventional synchronous induction motor, a gas vent hole has an oval shape having a short axis in a direction of a q axis and a long axis in the direction of a d axis, so that widths of electromagnetic steel sheets at both sides of the gas vent hole can be made thick, a width of a magnetic path in the direction of d axis is secured, and the magnetic flux can easily pass in the direction of d axis. However, in this structure, the magnetic flux can easily flow also in the direction of q axis, which causes a problem that a large salient pole difference cannot be obtained.